In recent years, as disclosed in PTL 1, a CMOS image pickup device, for example, for use in an imaging apparatus such as a digital camera may include an increased number of pixels because of miniaturization of pixels and are capable of capturing high-definition images. Recent imaging apparatuses for consumers may generally include 10 million pixels or more.
FIG. 16 is a configuration block diagram of such a general imaging apparatus. Referring to FIG. 16, an image pickup device 1500 includes a pixel part 1501, an AD conversion unit 1502, and a P/S conversion unit 1503. The pixel part 1501 converts a subject image to an electrical signal and outputs it to the AD conversion unit 1502.
The AD conversion unit 1502 converts an image signal read from the pixel part 1501 to a digital signal. The P/S conversion unit 1503 performs parallel-serial conversion on the digital signal converted by the AD conversion unit 1502. An image signal processing circuit 1600 performs a signal process on an image signal from the image pickup device 1500.
The imaging apparatus has a transfer path having a constant transfer capability for transferring an image signal from the image pickup device 1500 to the image signal processing circuit 1501. Thus, an increased number of pixels in the image pickup device may relatively result in an increased transfer time of all image signals of a subject.
In other words, the speed for reading signals from the image pickup device 1500 to the image signal processing circuit 1501 may be a bottleneck of the speed for reading out image signals. Furthermore, such high speed transfer may increase the amount of power consumed and the amount of heat generated by the transfer circuit and the processing circuit, which may reduce the precision of the data transfer.
In HDR photographing processing, an imaging element is used to capture a plurality of images with different exposures, and data of the plurality of images is output to an image processing circuit provided externally to the image pickup device and is synthesized to generate an HDR image. This processing may require transmission of data of the plurality of images to the image processing circuit provided externally to the image pickup device, which disadvantageously may increase the amount of data to be transmitted from the image pickup device to the image processing circuit and also increase power consumption.